Explanation
The "recover" function of the NIST cybersecurity framework is concerned with planning for resilience and timely repair of compromised capacities and service. This is because the recover function helps organizations to restore normal operations as quickly as possible after a cybersecurity incident, while also learning from the incident and improving their security posture. The other options are not part of the recover function, but rather belong to the identify (B), respond C, or protect (D) functions.

Explanation
A limitation of intrusion detection systems (IDS) is that they cannot detect application-level vulnerabilities. An IDS is a tool that monitors network traffic or system activity and alerts on any suspicious or malicious events.
However, an IDS cannot analyze the logic or functionality of applications and identify vulnerabilities such as SQL injection, cross-site scripting, or broken authentication.

Asymmetric algorithms are commonly used to securely distribute symmetric keys. The asymmetric encryption process involves a public key for encryption and a private key for decryption. This method ensures that even if the public key is intercepted, the encrypted data cannot be decrypted without the corresponding private key. Symmetric keys are then used for the bulk encryption of data due to their efficiency in processing large volumes of information.
Reference = The use of asymmetric algorithms for key distribution is a well-established practice in the field of cryptography. It is mentioned in various ISACA resources that asymmetric encryption, such as RSA and ECC, is crucial for secure communications, especially for the initial exchange of symmetric keys, which are then used for encrypting data streams or bulk data123.

Explanation
An objective of public key infrastructure (PKI) is to independently authenticate the validity of the sender's public key. PKI is a system that uses cryptographic keys to secure communications and transactions. PKI involves a trusted third party called a certificate authority (CA) that issues digital certificates that link a public key with an identity. The recipient can use the CA's public key to verify the sender's certificate and public key.

Availability can be protected through the use of redundancy, backups, and business continuity management. This is because these measures help to ensure that systems, data, and services are accessible and functional at all times, even in the event of a disruption or disaster. The other options are not directly related to protecting availability, but rather focus on enhancing confidentiality (A), integrity C, or awareness (D).